Switching regulators are used to convert a direct current (DC) voltage into a different, stable DC voltage with high efficiency. They are often used in electronics, such as mobile phones and computer equipment.
Switching regulators generally use one or more switching components, such as field effect transistors (FETs) or metal-oxide semiconductor FETs (MOSFETs) (collectively, FETs) to alternately couple and decouple a voltage source to a load. An output filter, such as an inductor and a capacitor, removes high frequency switching noise to produce the desired average output voltage.
A controller controls the switching components to maintain a substantially average output voltage over the load. A feedback loop provides an input to the controller. The feedback loop generally senses a level of an output voltage across the load, or a current through the load, and inputs that sensed level, in feedback, to the controller. The controller typically adjusts the duty factor (i.e., the portion of time that the output is switched high relative to the switching period) of the switching components in order to control the average voltage output by the output filter.
Current-mode control is another way of controlling the switching behavior of the switching components. Current-mode control achieves regulation of the output voltage through direct or indirect control of the average output current through the output filter and through the load.
Peak current control is one method of implementing current-mode control. With peak current control, the average output current through the load is controlled by controlling the peak current through the inductor. However, for a given peak inductor current, the average output current also depends on the inductor value, switching frequency, duty factor, input supply voltage, and output voltage. These additional dependencies affect the performance of the switching regulator. In addition, peak current control often requires additional compensation to prevent switching instability at duty factors above fifty percent.